JP2815069B2 - Process for producing polyethylene terephthalate-based polymers from lower dialkyl esters of dicarboxylic acids and glycols - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyethylene terephthalate (LDE) and glycol (GLY) from lower dialkyl esters of dicarboxylic acids (GDE) using a specific catalyst system and adding a small amount of dicarboxylic acid (DA). PET) -based polymers. The method of the present invention comprises:
It improves not only the transesterification time but also the polymerization time. In particular, the catalyst system is composed of manganese (Mn), lithium (L
i), cobalt (Co) (optional), and antimony (Sb). More specifically, manganese and lithium are used as catalysts for the transesterification reaction, and cobalt and antimony are used as catalysts for the polycondensation step. In addition to the catalyst system, reduced pressure (vacuum-
during the final stage of the let-down) process or after
The addition of less than about 6.0% by weight of dicarboxylic acid, based on the amount of LDE used, further reduces the polymerization time,
Lower molar ratios of E / glycol can be used.

RELATED APPLICATIONS The present invention relates to a US patent application (application no.
/ 425,540: Filing date: October 23, 1989)
Is a partial continuation (CIP) application.

[0003] In the conventional method, typically, dimethyl terephthalate (DMT) and ethylene glycol (EG) are heated at about 180 to 230 ° C under atmospheric pressure in the presence of a catalyst (manganese).
Reaction at a temperature of In the presence of a suitable catalyst, these components undergo transesterification to produce bis (2-hydroxyethyl) terephthalate or "monomer" and methanol. 1 mol of DMT and ethylene glycol 2
The reaction normally carried out with ２2.4 mol is reversible and is brought to an end by removing the methanol formed. During the transesterification, the monomer is essentially the main product (without taking into account methanol), along with a small amount of low molecular weight polymer and unreacted components.

Next, the monomer is polymerized by a polycondensation reaction. In such reactions, the temperature is about 280-310
C. and the pressure is reduced to less than 1 mm Hg and carried out in the presence of a suitable polymerization catalyst (antimony). From this reaction,
Polyethylene terephthalate (PET) and ethylene glycol are obtained. Since such reactions are reversible,
Removal of the glycol as it is generated directs the reaction towards the formation of the polyester. This known method is described in US Pat. No. 4,501,878 to Adams.
No.

[0005] Although manganese is the preferred catalyst for the transesterification reaction, the amount of manganese used must be tightly controlled. If the amount of manganese present in the transesterification reaction is too low, the reaction time will be extremely long, whereas if the amount of manganese is too high, undesirable by-products will be formed during the polycondensation reaction and the polymer will not be tolerated. Separation occurs and the color deteriorates (resulting in poor polymer quality). Since many factors affect the reactivity of manganese, the most desirable manganese usage must usually be determined by trial and error. For example, the reaction temperature, the reaction pressure, the degree of mixing during the reaction, the purity of the raw materials, the presence or absence of other additives, etc. all affect the effectiveness of manganese.

In the conventional method, a suitable transesterification reaction time is obtained by using manganese. However, manganese is sequestered by a polyvalent phosphorus compound after transesterification or during polycondensation, and discoloration occurs. And help reduce undesirable by-products. In general, the conventional method uses about 50 ppm based on the expected polymer yield.
１５０150 ppm manganese is used as transesterification catalyst. When about 150 ppm or more of manganese is used, even if phosphorus is excessively used and manganese is blocked, polymer deterioration occurs. It is believed that this phenomenon occurs because phosphorus cannot form a complex with manganese to the extent necessary to prevent discoloration.

[0007] US Patent No. 3,70, issued to Hrach et al.
No. 9,859 discloses a multi-component catalyst system for producing polyesters. Among many catalysts,
Lithium, cobalt, manganese and antimony are indicated. While these catalysts are shown in the background section of the patent publication, the claimed invention is directed to a catalyst system comprising antimony, lead and calcium, and additionally strontium or barium. . Hr
also teach that pentavalent phosphorus compounds need to be used as stabilizers to avoid the formation of discolored polyesters.

[0008] US Patent 3,657, to Cohn,
No. 180 discloses a method for producing a polyester using lithium or a divalent metal compound as a catalyst. The publication claims that manganese is one of the divalent metals that can be used. For the process described in the Cohn invention, the order of mixing the various raw materials and adding the compounds is stated to be important. This method is carried out by reacting DMT with ethylene glycol under transesterification conditions in the presence of a lithium salt, and then adding manganese. The method also includes using manganese as a catalyst and adding lithium after the transesterification reaction. In each case, the second metal is always added after transesterification and is therefore not used as a catalyst.
In addition, the second metal is always added in excess of the amount of catalyst. The second metal, together with the slurry of glycol and a small amount of terephthalic acid, imparts lubricity to the polyester film in addition to the reduced pressure, a number of factors being greater than the amount of catalyst.

UK Patent No. 1,41 to Barkey et al.
No. 7,738 discloses a method for producing a polyester, and suitable transesterification catalysts include:
Inter alia, zinc, manganese, cobalt and lithium are mentioned. Preferred polycondensation catalysts include antimony compounds. However, other catalyst compounds are claimed in this document, and the above catalysts are only given as background information.

Various patents assigned to Eastman Kodak Company (GB 1,417,738 and 1,52)
No. 2,656, U.S. Pat. No. 3,907,754;
962,189 and 4,010,145) disclose a wide range of catalyst systems, including manganese, cobalt and antimony catalyst systems, in each of which phosphorus is used as a blocking agent. ing. Each of these catalysts is added at the beginning of the transesterification. These catalyst systems substantially increase (decrease) the transesterification time and thus generally reduce the overall process time required to process the feedstock into a polymer, but substantially improve the polycondensation time. Not done.

[0011] US Patent 3,48 to Busot
No. 7,049 discloses a manganese, sodium and antimony catalyst system. In addition, a small amount of terephthalic acid mixed in the glycol slurry is added to the reaction vessel (at 30 mmHg) during vacuum depressurization to improve the polymerization rate and the like.

Improvements that reduce the transesterification time but not the polycondensation time are not particularly advantageous, for example, especially when different reaction vessels are used for the transesterification reaction and the polycondensation reaction. If different reaction vessels are used, reducing the transesterification time alone does not necessarily reduce the overall process time, as the speed of the entire process depends on the speed of the slowest step in the process. Therefore, reducing the time of one of the two stages does not improve the overall process. In such a case, additional reaction vessels can be obtained for the latest stage to improve overall process time, but this is a costly solution.

In addition to improving the transesterification and polycondensation rates, it is desirable to use a lower GLY / DMT molar ratio, ie, less than 2/1, as is conventionally known. Chemically, GLY and DMT are present in PET at a molar ratio of 1: 1; however, the usual method is to use at least a 100% excess of GLY (ratio 2: 1).
It is necessary to obtain the required degree of transesterification and the high molecular weight of the polymer, to reduce the yield and to avoid side reactions which give the polymer a low color and low clarity. Furthermore, GLY / D
Lowering the MT ratio usually results in a significant increase in processing time when using a Mn / Sb catalyst.

There is a need to develop catalyst systems and processes that reduce not only the transesterification reaction time but also the polycondensation reaction time and substantially reduce the overall processing time.

It is a further object or feature of the present invention to not only rapidly produce PET-based polyesters from raw materials, but also to produce polyesters having acceptable clarity, IV and color properties. is there.

It is a further feature of the present invention to obtain polymer yield, color and clarity while reducing the GLY / LDE molar ratio to less than 2: 1 during the production of the PET-based polymer. is there. Further, even if the molar ratio of GLY / LDE is reduced, the addition of dicarboxylic acid using a specific catalyst system does not significantly delay the polycondensation time.

SUMMARY OF THE INVENTION The present invention combines a catalyst effective in a transesterification reaction with a catalyst effective in a polycondensation reaction, uses these catalysts in specific amounts, and uses such catalysts in a unique manner in polyethylene terephthalate (PET). ) Introducing into the process for producing the base polymer, not only an improvement in transesterification time but also an improvement in polycondensation time is achieved. In particular, the present invention includes a catalyst system comprising manganese and lithium for use in transesterification reactions and a cobalt (optionally used) and antimony catalyst for use in polycondensation.

Further, the present invention also relates to a vacuum-
a small amount of dicarboxylic acid (DA) so that low GLY / LDE ratios can be used without compromising processing time, polymer yield, color and clarity Is what you do.

In its broadest concept, the present invention is a process for preparing a PET-based polyester from a lower dialkyl ester of a dicarboxylic acid (LDE) and a suitable glycol, comprising the following steps: glycol and LD
E in a molar ratio of about 1.4 / 1 to about 2.5 / 1 at a suitable temperature and pressure and in the presence of an effective amount of a manganese and lithium catalyst sufficient to produce monomers and alcohols. React; remove the resulting alcohol to allow the LDE to react with the glycol more completely; reduce the pressure to a reduced pressure sufficient to initiate the polycondensation; Below, an effective amount of antimony catalyst,
And optionally but preferably polymerizes in the presence of a cobalt catalyst to produce a PET-based polyester; sufficient to increase the rate of polycondensation during or after the final step of reducing the pressure to reduced pressure. Adding a suitable amount of dicarboxylic acid;

In its broadest concept, the present invention relates to a PET-based product produced by the above process.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyethylene terephthalate (PET) based polymers of the present invention are prepared from lower dialkyl esters of dicarboxylic acids (LDE) and glycols. Suitable LDEs include dimethyl terephthalate, dimethyl isophthalate, diethyl terephthalate, diethyl isophthalate, dipropyl terephthalate, dipropyl isophthalate, dibutyl terephthalate, dibutyl isophthalate, dialkyl naphthalates such as 2,6-dimethyl naphthalate Or a mixture of two or more of these. Examples of the glycol (GLY) include ethylene glycol, diethylene glycol, polyethylene glycol, a mixture of ethylene glycol and propane and / or butanediol, or a mixture of two or more thereof. The present invention can be used to produce PET-based polymers by either continuous or batch methods, both of which are well known in the art.

The catalyst system of the present invention comprises from about 10 ppm to about 150 ppm manganese (Mn); from about 50 ppm to about 250 ppm lithium (Li), based on expected polyester yield.
Optionally but preferably from about 10 ppm to about 40 p
pm cobalt (Co); and about 200 ppm to about 400 ppm
Antimony (Sb). The catalyst system, when used in the most effective amount, increases the transesterification and polymerization rates, thereby reducing both transesterification and polycondensation times. In addition, during or after the final stage of the reduced pressure step, a small amount of dicarboxylic acid (DA) is added,
Particularly when the glycol / LDE molar ratio used is low,
The polycondensation time is further reduced.

Generally, Mn and Li are added before or during the start of the transesterification reaction. In cases where the color of the polymer is important, at the end of the transesterification or at any point in the polycondensation, the manganese is blocked by adding a blocking agent as described in detail below. Sb and Co can be added before or during the start of the polymerization, as described more fully below.

The ability to add manganese and lithium before or at any point during transesterification involves adding the catalytic metal into the LDE, glycol or other feed stream. For example, some or all of the transesterification catalyst can be added to the glycol feed stream. Further, if the feed stream also contains other additives such as colorants, matting agents, opaquing agents, a catalyst for the transesterification step (manganese and lithium) may be included in the additive feed stream. Part.

The fact that the cobalt and antimony can be added at any time before or during the polymerization means that the antimony can be optionally added to the LDE, glycol or other feedstock stream along with other catalyst systems for manganese and lithium. Means that they can be added at the time. On the other hand, cobalt can be added only after the transesterification reaction has been substantially completed. If cobalt is added before the transesterification reaction is substantially completed, the transesterification reaction rate is slowed. Addition of antimony with the other catalyst in the feed stream or with cobalt after the transesterification reaction does not make a difference in the resulting polymer.

Although metals have been described for the catalyst system of the present invention, the catalyst can be added in the form of many different compounds. For example, compounds such as oxides and acetates are most preferred, but carbonates, phosphates (excluding manganese phosphate), halides, sulfides, amines, VIs
Organic and inorganic compounds, such as group III compounds, can also be used. Preferably, manganese, lithium and cobalt are added as catalysts in the form of acetate, while antimony is generally added in the form of antimony oxide. All compounds can also be used in glycolated form by pre-reaction with glycol.
If the catalyst is added in the form of a compound, the amount of compound added is determined by the amount of metal catalyst desired and the amount of available metal catalyst in the compound.

Other additives, such as colorants, matting agents, opacifiers, stabilizers, etc., can be included during the general process described above. These additives are not added to or removed from the essential components of the present invention.

Suitable dicarboxylic acids have the formula: Of, for example, succinic acid, glutaric acid, adipic acid,
Pimelic acid, suberic acid, azelaic acid, sebacic acid and fumaric acid; and dicarboxylic or tricarboxylic acids of benzene and naphthalene such as phthalic acid, isophthalic acid and terephthalic acid, trimellitic acid and trimesic acid, and two or more thereof Is a mixture of The preferred DA is terephthalic acid. Unmodified PET using this
It is because it can manufacture.

In the method of the present invention, GLY and LD
E at a temperature of 150-250 ° C. and a pressure of approximately atmospheric pressure,
The reaction is carried out in a transesterification reaction by a batch method or a continuous method to obtain a monomer and an alcohol. LDE and GL
Y is reacted in the presence of manganese and lithium and generally has a GLY / LDE molar ratio of, for example, about 1.4 / 1 to 2.5 / 1, preferably 1.6 / 1 to 1.8 / 1. It is made to react with. Since the transesterification reaction is reversible, the alcohol formed is removed to allow the reaction to proceed with the monomer-
It is necessary to proceed in the direction of producing bis (2-hydroxyethyl) terephthalate (when dimethyl terephthalate and ethylene glycol are used).

It is believed that lithium initiates the transesterification of LDE with glycol at temperatures below the effective temperature range of manganese. While applicants do not wish to be bound by this theory, it is believed that the addition of lithium to manganese in the transesterification reaction increases transesterification rates, thereby reducing transesterification time.

The catalytic reactivity of manganese occurs at higher temperatures than lithium. Manganese has extremely high reactivity in both transesterification and polycondensation reactions. It is generally preferred to block manganese during the polycondensation reaction to render it ineffective and inert, especially when the polyester is used in applications where color is important, such as fabrics. Unblocked manganese gives poor color polymers, which generally have an undesired broad molecular weight distribution and, if manganese is active as a catalyst in the polycondensation stage, oxides, carboxyl groups, etc. Many undesirable by-products are formed.

[0032] Typical sequestering agents are polyvalent phosphorus compounds.
Therefore, at the end of the transesterification reaction or during the polycondensation reaction, usually a tetravalent or pentavalent phosphorus compound is added. Representative phosphorus compounds suitable as sequestering agents for manganese are
Tributyl phosphate, polyphosphoric acid, triphenyl phosphite and the like. Phosphorus is believed to form a very stable complex with manganese, thus rendering manganese inactive during polycondensation. On the other hand, phosphorus is not considered to form a stable complex with any of lithium, cobalt and antimony. Thus, each of these compounds becomes reactive if the conditions (such as temperature) that make them catalysts for the production of PET-based polymers are achieved.

It should be noted that phosphorus compounds do not block all of the manganese. Therefore, when choosing the level of manganese, keep in mind that the use of manganese will result in a less colored polymer, produce undesirable by-products, and have a broader molecular weight distribution of the resulting polymer. I have to put it. In the present invention, it is desirable that manganese and lithium as the transesterification catalyst be balanced so as to control the reactivity, the reaction rate and the side reaction so as to obtain a high quality product. Thus, using a sufficient amount of manganese to further increase the transesterification rate than would be obtained when using only lithium,
It is important that a sufficient amount of lithium be used to achieve good color of the polymer, eliminate side reactions, and make the molecular weight distribution of the polymer narrower, which are advantages of lithium catalysts. In addition, the lithium catalyst is also active during the polycondensation reaction because it is not blocked, which can result in a reduction in total polycondensation time over catalyst systems using antimony alone.

After sequestering the manganese, a polycondensation catalyst can be added. Cobalt, manganese, and lithium transesterification catalyst systems actually slow the transesterification rate, increase transesterification times over those with manganese and lithium catalyst systems, and are used in applications where color is important. It is important that no cobalt be added during the transesterification reaction, since it has been found that an unacceptable gray polymer is formed. Since cobalt cannot be added until the transesterification reaction is substantially complete, it is advantageous to add the cobalt with the sequestering agent or more preferably shortly after the sequestering agent is added. Similarly, antimony can be added at or shortly after the addition of the sequestering agent.

On the other hand, the antimony catalyst can be added together with various feed streams in the same manner as the manganese and lithium transesterification catalysts. Antimony is not effective during the transesterification reaction because the temperature of the transesterification reaction is lower than the reaction temperature of antimony for the production of polyester polymers. Thus, antimony may be added at any point before or during the polycondensation reaction.

After the transesterification reaction is completed, the monomers are then subjected to a polycondensation reaction to form a PET-based polymer and a glycol. The polycondensation reaction is 250
It occurs in a temperature range of ３１０310 ° C. and under a reduced pressure of about 0.1-3 mmHg. The reaction is reversible, thus continuously removing the glycol, driving the completion of the reaction towards the formation of a PET-based polymer. Between the transesterification reaction and the polycondensation reaction, it is necessary to reduce the pressure from the transesterification reaction pressure to the pressure required in the polycondensation reaction. This time is typically referred to as vacuum-let-down time. Under circumstances where it is necessary to release the reaction vessel to release the reduced pressure and start the reduced pressure again, it is preferable to add a cobalt and antimony polycondensation catalyst before starting the reduced pressure.

[0038] Lithium and antimony increase the rate of polycondensation and are about 2% based on the expected yield of polyester.
Addition of between 0 ppm and 40 ppm of cobalt to the polycondensation reaction as needed increases the rate of the polycondensation reaction beyond that obtained with lithium and antimony catalyst systems, thereby increasing the yield of lithium and antimony. The polycondensation time is further reduced than is possible.

Generally, it is not desirable to use any amount of catalyst outside the scope of the present invention. Using an amount less than the minimum amount described for any catalyst generally results in results that are not substantially identical to those obtained using the present invention. Using amounts above the maximum amount stated for any catalyst will have undesirable effects such as poor color, unwanted by-products, high cost, and the like.

To further increase the polycondensation rate and thereby reduce the polycondensation time, a small amount of dicarboxylic acid (DA) is added during or after the vacuum depressurization. In general, amounts of less than 6.0% by weight, based on the weight of LDE used, are sufficient. If the amount of DA added is too low (generally less than about 0.5% by weight), the polycondensation time is not significantly reduced. If the amount of DA added is too high (generally greater than about 6.0% by weight), the reaction rate will be lower than without the DA addition.

In addition to the above, it is believed that lithium forms a salt complex with DA, making it more soluble and more reactive with glycols, further improving the overall PET yield.

Finally, using the catalyst system of the present invention with the addition of small amounts of DA, the process for making PET-based polymers can be performed at a much lower GLY /
It has been found that this can be done using the LDE molar ratio. Previously, a suitable glycol / DMT molar ratio was in the range of 2.0 to 2.4 (U.S. Pat.
501,878). According to the present invention, GLY / L
The molar ratio of DE may range from 1.4 / 1 to 2.5 / 1. Preferably the GLY / LDE molar ratio is 1.6 /
1 to 1.8 / 1. With this preferred range,
The shortest transesterification and polycondensation times result in good quality polymers that can be produced more efficiently than conventional ones.

During depressurization and depressurization, the pressure is about 3.
It is reduced to 0 mmHg or less. DA is added at the final stage or after completion of the reduced pressure, ie, when the reduced pressure is from about 250 mmHg to about 0.3 mmHg and the temperature of the reaction vessel is about 250 to about 290 ° C. Before decompression or decompression or decompression is about 250 mm
If DA is added before reaching Hg, the polycondensation time is not significantly improved. Immediately prior to reduced pressure, the hydroxyl (glycol) / carboxyl group ratio is about 2: 1. The polycondensation reaction is most efficient when this ratio reaches about 1: 1. As the vacuum is reduced to reduce the pressure and increase the temperature, glycol distills out, thereby reducing the amount of hydroxyl in the reaction vessel. Adding DA (carboxyl) between atmospheric pressure (pressure during transesterification) and about 250 mmHg requires a very large amount of DA to balance the hydroxyl / carboxyl ratio, and increases solubility and reaction temperature. Problems such as descent occur. Furthermore, if too much DA is added, excess carboxyl cannot be removed, and the polycondensation reaction rate is greatly reduced, and the polycondensation time is increased. The excess hydroxyl is preferred over the carboxyl excess, since the excess hydroxyl can be removed by evaporation.

DA is added after the reduced pressure has reached about 250 mmHg or less (during or after completion of the reduced pressure). DA
Is added in an amount of 0.5 to 6.0% by weight based on the weight of LDE used. When DA is added at the end of reduced pressure reduction, the preferred amount of DA added is 1.0-1.5% by weight.
Range. If DA is added at about 250 mmHg during reduced pressure, the preferred amount of DA added is about 6.0.
% By weight.

DA can be added as a solid or in the form of a slurry with glycol (any of the glycols described above can be used).
The weight percentage of DA / glycol is 80 / 20-30 / 70
It may be. If more than 80/20 DA is added to the glycol, the slurry will be too viscous to be pumped. Slurries with high amounts of glycol and less than 30/70 will have poor hydroxyl / carboxyl equilibrium.

When the molar ratio is less than 1.6 / 1,
It is preferred to use a more active catalyst (titanium) during transesterification to ensure a high degree of transesterification. GL
When the molar ratio of Y / LDE is greater than 1.6 / 1,
It is not advantageous to add titanium as this will cause degradation and discoloration of the polymer.

Experimental Step An autoclave batch (about 1000 g of polymer was prepared) was prepared, and a batch for a preliminary experiment was carried out in a batch process at a molar ratio of ethylene glycol (EG) / DMT of about 2.1 / 1. While the batch for the example is E
The experiment was performed at a G / DMT molar ratio of about 2.08 to 1.55. The autoclave was initially charged with DMT, ethylene glycol and various indicated catalysts. The following preliminary facts
When using manganese, lithium or cobalt in the experiments and examples, these metals were added in the form of acetate, antimony in the form of oxides, and the amount of catalyst added was determined based on the metal itself. The autoclave is then brought to atmospheric pressure for about 1 hour, at which point transesterification commences.
Heated to 55 ° C. The autoclave was flushed with an inert gas (4 standard cubic feet / hour of nitrogen) to help prevent oxidation during the loading of the raw materials. Generally, the autoclave is agitated with a stirrer to ensure uniform mixing of the raw materials. At the start of the transesterification reaction (approximately when the contents of the reaction vessel reached 155 ° C.), the flow of nitrogen gas was stopped and the start time was recorded. The temperature during transesterification rose from 155C to about 220-230C. During the transesterification, methanol was continuously removed to direct the reaction towards monomer formation. at this point,
The transesterification reaction was substantially completed, and polyvalent phosphorus (eg, tributyl phosphate) was added to block the manganese. Nitrogen gas was passed again during the addition and mixing of the phosphorus compound.

Once the phosphorus was sufficiently and uniformly mixed with the monomer, the indicated amount of polycondensation catalyst was added. Vacuum pressure reduction was started, during which the nitrogen flow was stopped again. During decompression and decompression,
The autoclave was evacuated until a vacuum of about 1.0 mmHg was achieved. At the end of the reduced pressure, the autoclave was heated again to 270 ° C., thereby initiating the polycondensation reaction. In an embodiment , DA is reduced
(Except for Experimental Example 1 (Comparative Example)) , an amount of 1.0 to 2.0% by weight based on the amount of LDE used was added. The polycondensation reaction was carried out until substantially complete, during which the glycol formed was removed. The polycondensation time was recorded.

Once the polyester has formed, the polymer is
Intrinsic viscosity number (IV), color, melting point, glass transition temperature, number of carboxyl end groups (CEG) (expressed in microequivalents per gram), diethylene glycol present (DE
G) and the presence of various catalyst components. The color test was based on ASTM method E308-85 and measured the luminescence (L *), yellow-blue tint (b *) and red-green tint (a *) of the polymer. The IV was tested using orthochlorophenol solvent at 25 ° C. by mixing 8 g of the polymer with 100 ml of solvent. Melting points and Tg were measured with a differential scanning calorimeter.

Preliminary Experiments The present invention is demonstrated using various catalyst systems. In Preliminary Experiment 1, manganese and antimony were converted to about 61 ppm manganese and about 49 ppm antimony based on the expected yield of the polymer.
Used at 0 ppm. Manganese was in the form of manganese acetate and antimony was in the form of antimony oxide. The components were added as described above under various experimental conditions. At the end of the transesterification, 88 ppm of phosphorus was added.

Preliminary Experiment 2 is similar to Preliminary Experiment 1, except that a smaller amount of manganese (13 ppm) was used as the transesterification catalyst and a slightly smaller amount of antimony (409 ppm) was used as the polycondensation catalyst. went. At the end of the transesterification, 88 ppm of phosphorus was added.

In Preliminary Experiment 3, manganese and cobalt were used as transesterification catalysts, and antimony was used as a polycondensation catalyst. The amount of manganese was 75 ppm, the amount of cobalt was 20 ppm, and the amount of antimony was 328 ppm. Cobalt was added at the same time as manganese. That is, these were charged together with the raw materials into an autoclave. At the end of the transesterification, 90 ppm of phosphorus were added.

In Preliminary Experiment 4, the same catalyst system as in Preliminary Experiment 3 was used, except that cobalt was added after the transesterification step, and only 75 ppm of manganese was used as the transesterification catalyst. 20 ppm of cobalt and 328 ppm of antimony were used as polycondensation catalysts. 9 at the end of transesterification
0 ppm of phosphorus was added to the autoclave.

Preliminary experiment 5 shows that as a transesterification catalyst,
Manganese, lithium and cobalt, all in the form of acetate, were used. More specifically, manganese 27 ppm, lithium 144 ppm
And 20 ppm of cobalt. In the polycondensation step, 376 ppm of antimony was added before the polycondensation step. At the end of the transesterification reaction, 90 ppm of lithium were added.

In preliminary experiment 6, manganese and lithium were added as catalysts for the transesterification reaction, and cobalt and antimony were added as catalysts for the polycondensation step. Specifically, 27 ppm of manganese and 144 ppm of lithium were added in the form of acetate, 20 ppm of cobalt were added in the form of acetate after transesterification, and 376 ppm of antimony were added in the form of oxide. At the end of the transesterification reaction, 90 ppm of phosphorus were added.

The reaction time, IV, melting point, Tg, colorant, reduced pressure reduction time, CEG, DEG, and amount of catalyst were measured. Table 1 shows the results of the preliminary experiment .

[0056]

[Table 1]

Preliminary experiment 1 shows that when manganese is used as a transesterification catalyst and antimony is used as a polycondensation catalyst,
The transesterification time was about 167 minutes, the polycondensation time was about 111 minutes, and the total of these times was 278 minutes. Preliminary experiment 2 shows that the transesterification time is significantly affected (increased) by reducing the level of manganese.

Preliminary Experiment 3 shows that the use of cobalt as the transesterification catalyst affects the transesterification time by reducing the transesterification time by about 47 minutes. For this particular preliminary experiment , 490 ppm of antimony was used in preliminary experiment 1, whereas the amount of antimony used was 328 ppm.
The polycondensation time increased. This preliminary experiment also shows poor color and higher CEG when using cobalt as transesterification catalyst.

In Preliminary Experiment 4, the same amount of cobalt, manganese and antimony as in Preliminary Experiment 3 was used, however, cobalt was used as a polycondensation catalyst. Preliminary experiment 1
, But the polycondensation time was considerably longer than in Preliminary Experiment 1. However, the polycondensation time of Preliminary Experiment 3 was shorter. This indicates that cobalt is an effective polycondensation catalyst. In addition, in Preliminary Experiment 4, a polymer of good color was obtained.

In preliminary experiment 5, lithium, manganese and cobalt were the transesterification catalysts, but only antimony was the polycondensation catalyst. Both transesterification time and polycondensation time for preliminary experiment 5, preliminary experiment 1
It was larger and better. Since cobalt is used as a transesterification catalyst, the color is inferior (brightness) and CE
G was high. Adding lithium lowers DEG.

In Preliminary Experiment 6, manganese and lithium were used as transesterification catalysts, and cobalt and antimony were used as polycondensation catalysts. The amount of catalyst was equivalent to the amount used in Preliminary Experiment 5. In Preliminary Experiment 6, excellent color characteristics, acceptable CEG levels, and excellent low levels of DEG were obtained. Most importantly, both transesterification and polycondensation times were significantly reduced. Preliminary result
Comparison of Experiment 5 with Preliminary Experiment 6 clearly shows that the addition of cobalt as a transesterification catalyst interferes with the catalytic activity of manganese and lithium. Preliminary experiment 6
The improved polycondensation time obtained in is a result of using cobalt as the polycondensation catalyst.

EXAMPLE In this example, a small amount of terephthalic acid (TA) in the form of a solid or in the form of a glycol slurry (TA: 60% by weight, EG: 40% by weight) was introduced after reducing the pressure under reduced pressure. The experimental procedure was repeated. For comparison purposes, the amount of terephthalic acid and the point at which the acid is added during the process ( S
After tellurium exchange (after transesterification and before pressure reduction ) or during pressure reduction. Further, the molar ratio of EG / DMT was varied between 1.55 and 2.08. In some experiments, when the molar ratio was less than about 1.8, the transesterification temperature was increased to 235 ° C. to accelerate the chemical reaction (Examples 5, 7, 9 and 11). In other cases, the transesterification temperature was 225 ° C and the polycondensation temperature was 2
85 ° C. Also, at lower molar ratios of about 1.6 or less (Examples 12 and 13), a hotter and more active catalyst (titanium) was added. However, titanium is known to degrade and discolor the polymer. These effects can be mitigated by controlling the amount of titanium added.

Experimental Example 1 (Comparative Example) and Experimental Example 4 (Comparative Example)
Example), Experimental Examples 2, 3 and 6 use the same catalyst system, but Experimental Examples 5, 7 and 11 have twice the amount of manganese. Experimental Example 8 shows the effect of not using a cobalt catalyst as compared to Experimental Example 7. Experimental Example 9 shows the effect of reducing the amount of lithium used by half compared to Experimental Example 7. Experimental examples 12 and 13 were EG / DM
This shows the effect of lowering the molar ratio of T and adding titanium. Experimental Example 10 (Comparative Example) shows the effect of using a Mn / Na transesterification catalyst system. The results of the examples are shown in Table 2 below.

[0064]

[Table 2]

[0065]

Results Using a Mn / Li / Sb / Co catalyst system, E was added by adding a small amount of DA [terephthalic acid (TA)] after reducing the pressure under reduced pressure.
I and PC times are shorter. When the molar ratio is about 2.0 / 1, after transesterification (after transesterification,
The reaction rate was delayed when TA was added ( before pressure) (Experimental Example 1)
(Comparative example)). Even when using the conventional EG / DMT molar ratio, the use of a small amount of DA increases the polycondensation rate and consequently reduces the polycondensation time. Surprisingly, EG / D
The PC time was also dramatically reduced when using lower molar ratios of MT (Examples 5, 9, and 11). Raising the transesterification temperature to 235 ° C. (from 225 ° C.) requires E
It has been found useful when the G / DMT molar ratio is less than 1.6. It is useful to add a titanium catalyst when the EG / DMT molar ratio is less than 1.6 (Examples 11 and 12). The Mn / Na transesterification catalyst system is
Very poor effectiveness compared to n / Li catalyst system.

Example 5 was repeated with the addition of 1.5% by weight of adipic acid instead of TA. Transesterification time is 96
Minutes and polycondensation time were 57 minutes, and the total time was 153 minutes. This is because the total time was 1 in the original Experimental Example 5.
This compares well with 56 minutes, indicating that a wide range of dicarboxylic acids can be used.

6% by weight of TA was added at 250 mmHg (during decompression), and 60 ppm of Mn was used (originally 27 pp).
Experimental Example 5 was repeated again. The transesterification time is 82 minutes, the polycondensation time is 85 minutes,
Total time was 167 minutes. This experiment shows that if less than 6% by weight of DA is used, the DA can be added at an early stage on the order of 250 mmHg.

Thus, according to the present invention, a catalyst system which fully satisfies the objects, aims and advantages set forth above, and a process for producing polyesters from lower dialkyl esters of dicarboxylic acids and glycols using such a catalyst system. It is clear that was provided. Although the invention has been described with respect to particular embodiments, it is evident that many substitutions, modifications and changes will be apparent to those skilled in the art. Therefore, all such substitutions, modifications and alterations are included in the spirit and scope of the present invention. The embodiments of the present invention are as follows. 1. A process for producing a polyester polymer based on polyethylene terephthalate from a lower dialkyl ester of a dicarboxylic acid and a glycol, comprising: (a) combining a lower dialkyl ester of a dicarboxylic acid and a glycol at a suitable temperature and pressure; And in the presence of an effective amount of a manganese and lithium catalyst by transesterification in a molar ratio of about 1.4 / 1 to about 2.5 / 1 to obtain an alcohol and a monomer; (b) during said transesterification (C) reducing the pressure to a reduced pressure sufficient to initiate polycondensation; and (d) at a suitable temperature and pressure and at an effective amount of The monomer is polymerized by polycondensation in the presence of an antimony catalyst to produce a polyester during or after the final stage of the vacuum stage. Polycondensation to increase the engagement of the speed of the addition of dicarboxylic acid sufficient effective amount of: said method characterized by comprising the step. 2. The method of claim 1 wherein an effective amount of cobalt is present during said polycondensation reaction. 3. The manganese, lithium and cobalt are in the form of acetate, and the antimony is in the form of oxide;
The method described in the section. 4. Based on the expected yield of the polyethylene terephthalate-based polyester polymer, the manganese is present in the range of about 10 ppm to about 150 ppm, the cobalt is present in the range of about 10 ppm to about 40 ppm, and the lithium is present in the range of about 50 ppm to about 50 ppm. The method of claim 2 wherein the antimony is present in the range of about 200 ppm to about 400 ppm. 5. After the transesterification reaction is substantially completed or during the polycondensation reaction, an effective amount of a sequestering agent (sequestering agen
the fourth of which blocks the manganese by adding
The method described in the section. 6. 6. The method according to the above item 5, wherein the blocking agent is a polyvalent phosphorus compound. 7. The method of claim 1 wherein said transesterification is carried out in a temperature range from about 150 to about 250C and at about atmospheric pressure. 8. The method of claim 1 wherein said pressure reducing step reduces pressure to less than about 3 mm Hg and raises the temperature of said polycondensation reaction to a range from about 255 to about 310 ° C. 9. Adding said effective amount of dicarboxylic acid during said depressurizing step and after the depressurized pressure is below about 250 mmHg.
The method described in the section. 10. The method of claim 9 wherein the effective amount of dicarboxylic acid is less than 6.0% by weight based on the expected yield of the polyethylene terephthalate-based polymer. 11. The dicarboxylic acid is of the following formula: OO ‖ HO-C- (CH ₂ ) _x -C-OH (where x> 2), for example, succinic acid, glutaric acid, adipic acid, pimerine Acids, suberic, azelaic, sebacic and fumaric acids; and benzene and naphthalene dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; and benzene and naphthalene tricarboxylic acids such as trimellitic acid and trimesic acid Item 11. The method according to Item 10, wherein the method is selected from the group consisting of acids; and mixtures thereof. 12. 10. The method of claim 9 wherein said dicarboxylic acid is added in solid form. 13. The method of claim 9 wherein said dicarboxylic acid is added in the form of a slurry with glycol. 14． The method of claim 1 wherein the glycol / lower dialkyl ester molar ratio is from about 1.6 / 1 to about 1.8 / 1. 15. The method of claim 1, wherein the glycol / lower dialkyl ester molar ratio is less than about 1.6 / 1. 16. 16. The process of claim 15 wherein said transesterification and polymerization steps are performed in the presence of an effective amount of a titanium catalyst. 17． The lower dialkyl ester is selected from the group consisting of dimethyl terephthalate, dimethyl isophthalate, diethyl terephthalate, diethyl isophthalate, dipropyl terephthalate, dipropyl isophthalate, dibutyl terephthalate, dibutyl isophthalate, dimethyl naphthalate and a mixture of two or more of these. A method according to claim 1, which is selected. 18. The above-mentioned item 1, wherein the glycol is selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol, a blend of ethylene glycol and propanediol, a blend of ethylene glycol and butanediol, and a mixture of two or more thereof. The method described in. 19. 2. A polyethylene terephthalate polymer obtained by the method according to the above item 1.

 ──────────────────────────────────────────────────続 き Continuing the front page (72) Inventor Bobby Neil Far, Carolina Acres, Fort Mill, South Carolina, USA 2140 (56) References JP-A-1-275628 (JP, A) 58-55974 (JP, B2)

Claims (3)

(57) [Claims] 1. A process for producing a polyester polymer based on polyethylene terephthalate from a lower dialkyl ester of a dicarboxylic acid and a glycol, comprising the following steps: (a) combining a lower dialkyl ester of a dicarboxylic acid with a glycol; / The molar ratio of the ester is about 1.4
/ 1 to about 2.5 / 1 at a suitable temperature and pressure,
And 10 ppm to 10% based on the expected yield of the polyester polymer based on the polyethylene terephthalate.
Reacting by transesterification in the presence of 150 ppm manganese and 50 ppm to 250 ppm lithium to obtain alcohol and monomer; (b) removing the alcohol during the transesterification to improve the yield of the monomer; (C) reducing the pressure to a reduced pressure sufficient to initiate polycondensation; (d) at a suitable temperature and pressure and based on the expected yield of the polyethylene terephthalate-based polyester polymer, from 200 ppm to 400 ppm. Polymerizing the monomer by polycondensation in the presence of antimony; then (e) during or after the final stage of the vacuum stage, the polyester
Used to increase the rate of polycondensation to produce
A sufficient effective amount of dialkyl ester based on
Including a step of adding a carboxylic acid, provided that the dicarboxylic acid is added during reduced pressure reduction,
The amount of dicarboxylic acid depends on the amount of lower dialkyl ester used.
0.5 to 6% by weight based on the weight of the dicarboxylic acid.
The amount of rubonic acid is based on the amount of lower dialkyl ester used.
The above-mentioned method, wherein the amount is 1.0 to 1.5% by weight . 2. The method according to claim 1, wherein an effective amount of cobalt is present in the polycondensation reaction step (d). 3. The method according to claim 1, wherein the manganese is blocked by adding an effective amount of a blocking agent after the transesterification reaction is substantially completed or during the polycondensation reaction.